Thermoplastic resin composition having electromagnetic interference shielding properties

Abstract

A thermoplastic resin composition having good electromagnetic shielding properties and high stiffness comprising thermoplastic polymer, metal alloy having a melting point of between about 200° C. and 500° C.

1. A thermoplastic resin composition comprising:
 (a) about 30 to about 78 volume percent of at least one thermoplastic polymer; 
 (b) about 2 to about 20 volume percent of at least one metal alloy having a melting point of between about 200° C. and 500° C., wherein said metal alloy is at least one selected from the group consisting of Sn—Cu, Sn—Al, Sn—Zn, Sn—Te, Sn—Pt, Su—P, Sn—Mn, Sn—Ag, Sn—Ca, Sn—Mg, Sn—Au, Sn—Ba, Sn—Ge, Al—Li, Cu—Li, and Zn—Li; and 
 (c) greater than 20 to about 50 volume percent of carbon fibers, having a thermal conductivity of less than 50 W/mK, 
 
       wherein the volume percentages are based on the total volume of the composition. 
     
     
       2. The composition of  claim 1 , wherein (b) is at least one metal alloy having a melting point of between about 200° C. and about 400° C. 
     
     
       3. The composition of  claim 1 , wherein the carbon fibers (c) comprise polyacrylonitrile fibers, pitch fibers, cellulose fibers, and/or carbon nanotubes. 
     
     
       4. The composition of  claim 1 , wherein the thermoplastic polymer comprises at least one polyamide. 
     
     
       5. The composition of  claim 4 , wherein the polyamide is one or more selected from the group consisting of polyamide 6; polyamide 6, 6; polyamide 4, 6; polyamide 6, 9; polyamide 6, 10; polyamide 6, 12; polyamide 10, 10; polyamide 11; polyamide 12; semi-aromatic polyamides such as poly(m-xylylene adipamide) (polyamide MXD, 6), poly(dodecamethylene terephthalamide) (polyamide 12, T), poly(decamethylene terephthalamide) (polyamide 10, T), poly(nonamethylene terephthalamide) (polyamide 9, T), the copolyamide of hexamethylene terephthalamide and hexamethylene adipamide (polyamide 6, T/6, 6); the copolyamide of hexamethyleneterephthalamide and 2-methylpentamethyleneterephthalamide (polyamide 6, T/D, T); the copolyamide of hexamethylene isophthalamide and hexamethylene adipamide (polyamide 6, I/6, 6); and the copolyamide of hexamethylene terephthalamide, hexamethylene isophthalamide, and hexamethylene adipamide (polyamide 6,T/6, I/6, 6), 
     
     
       6. The composition of  claim 1 , wherein the thermoplastic polymer comprises at least one polyester. 
     
     
       7. The composition of  claim 6 , wherein the polyester is one or more selected from the group consisting of poly(ethylene terephthalate), poly(1, 4-butylene terephthalate), poly(propylene terephthalate), poly(1, 4-butylene naphthalate), poly(ethylene naphthalate), and poly(1, 4-cyclohexylene dimethylene terephthalate). 
     
     
       8. The composition of  claim 1 , further comprising powders of at least one metal, where the metal is not a metal alloy having a melting point of between about 200° C. and about 500° C. 
     
     
       9. The composition of  claim 8 , wherein the metal powders are one or more selected from the group consisting of iron, copper, tin, nickel, aluminum, magnesium, titanium, chromium, zinc, gold, and silver. 
     
     
       10. A thermoplastic resin composition comprising:
 (a) about 30 to about 88 volume percent of at least one thermoplastic polymer; 
 (b) about 2 to about 20 volume percent of at least one metal alloy having a melting point of between about 200° C. and 500° C., wherein said metal alloy is at least one selected from the group consisting of Sn—Cu, Sn—Al, Sn—Zn, Sn—Te, Sn—Pt, Su—P, Sn—Mn, Sn—Ag, Sn—Ca, Sn—Mg, Sn—Au, Sn—Ba, Sn—Ge, Al—Li, Cu—Li, and Zn—Li; and 
 (c) about 10 to about 50 volume percent of carbon fibers having a thermal conductivity of less than 50 W/mK, 
 
       wherein the volume percentages are based on the total volume of the composition. 
     
     
       11. The composition of  claim 10 , wherein (b) is at least one metal alloy having a melting point of between about 200° C. and about 400° C. 
     
     
       12. The composition of  claim 10 , wherein the carbon fibers (c) comprise polyacrylonitrile fibers, pitch fibers, cellulose fibers, and/or carbon nanotubes. 
     
     
       13. The composition of  claim 10 , further comprising powders of at least one metal, where the metal is not a metal alloy having a melting point of between about 200° C. and about 500° C. 
     
     
       14. The composition of  claim 13 , wherein the metal powders are one or more selected from the group consisting of iron, copper, tin, nickel, aluminum, magnesium, titanium, chromium, zinc, gold, and silver. 
     
     
       15. The composition of  claim 10 , wherein the thermoplastic polymer comprises at least one polyamide and/or polyester. 
     
     
       16. A article made from the composition of  claim 1 . 
     
     
       17. The article of  claim 16  in the form an electrical or electronic housing, a motor core housing, or secondary battery case. 
     
     
       18. A article made from the composition of  claim 10 . 
     
     
       19. The article of  claim 18  in the form an electrical or electronic housing, a motor core housing, or secondary battery case.